Positive displacement fluid measurement systems may be used to measure a flow rate or volume of a fluid or gas. For example, dispensing systems may use feedback from a positive displacement fluid meter to control the volume of fluid dispensed. Such control systems are often used in lieu of time-on controls to more accurately dispense precise amounts of fluid or gas and is commonly used in a variety of settings including, but not limited to, the industrial, healthcare, pharmaceutical and food and beverage industries. For example, a positive displacement fluid meter may be used in the manufacturing process of a drug which requires accurate measurement of two materials to be mixed into a single batch. The positive displacement fluid meter may be installed in the supply lines of the respective materials and feedback from the meters may be used to dispense the appropriate amount of each material into a blend tank to be mixed. This application of a positive displacement meter, like many others, may require the positive displacement meter to have an accuracy of measurement (e.g., +/−0.5%) to comply with quality control or regulations, for example. Accordingly, ensuring that a positive displacement meter accurately measures a volume of fluid or gas can help ensure that a system or process performs its intended function.
In some configurations, the positive displacement meter comprises at least one rotating element, which rotates as fluid flows through the meter. The metered amount of fluid flowing through the meter corresponds to the rotational motion and position of the rotating element. In some configurations, however, the rotating element can rotate in the meter even if the appropriate fluid is not flowing through the meter. For example, when a fluid such as a product for making a solution is pumped through the meter, the product causes the rotating element to rotate within the meter as it is pumped. Once the product runs out, air can be pumped through the meter and instead of the product. The air can cause the rotating element to rotate without product flowing through the system, thus providing a false indication of product flowing through the meter.